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ANALYSIS OF PROJECT RELATED NOISE LEVELS Noise measurements and accepted noise modeling techniques were used to predict noise levels generated by aggregate mining operations at the proposed Traina site. Operational information was developed from discussions with Teichert staff and from BBA file data. Teichert staff reports that excavation activities at the Traina site would be conducted primarily using Caterpillar self-propelled elevating scrapers,such as the Model 633. Summer hours of operation in the mine pit are reported to be 6:00 a.m. to 6:30 pm, Winter hours(November-March) are reported to be 6:00 am to 2:30 pm, and worst-case operations during periods of peak demand would reportedly occur from 6:00 am to 10:30 pm. According to the plant manager, a total of 25 round trip scraper passages per hour would occur at the site, resulting in a total of 50 passages per hour on the access road. The proposed project access _ road will cross MacArthur Road and enter the existing Teichert rock plant without traveling on MacArthur Road. The approximate crossing location is shown on Figure 1. Noise emission data for fully loaded scrapers were taken from BBA noise measurements conducted at Teichert Tracy and Sacramento excavation areas,which were found to compare favorably to other BBA file data for similar scrapers. A mean Sound Exposure Level (SEL) of 95 dB at a distance of 50 feet was used to describe a single scraper passage at the Traina excavation site. Based on 50 such passages per hour at a mean SEL of 95 dB per passage, the average hourly(Leq) scraper noise level at a distance of 50 feet from the scraper passage area was computed to be approximately 75 dB. The nearest potentially affected noise-sensitive areas(residences)are located approximately 200 feet south of the southern boundary of the Traina excavation site. The general locations of these residences are shown on Figure 1. The predicted average hourly scraper noise levels at those locations during the closest mining operations (200 feet) are predicted to be approximately 66 dB Leq. Based on that data,the L. computed for worst-case (16 %z hour per day) operations would be approximately 67 dB when scrapers are operating 200 feet from those residences. The computed L.of 67 dB at the nearest residences exceeds the San Joaquin County exterior noise level standard of 65 dB Ld,,. If the scrapers refrained from operating within 400 feet of those residences during the 6:00 am and 10:00 pm hours, the 65 dB Ld„ standard would be satisfied at those two residential locations. No restrictions on scraper operations would be required during daytime hours to achieve compliance with the 65 dB Ld„ standard. 2